Power-Efficient Adaptable Wireless Sensor Networks

Distributed wireless sensor networks are expected to have widespread
applications within the coming decades, ranging from
military tracking and emergency response to habitat monitoring and
environmental tracking. These networks must be capable
of adapting to changing environments and requirements. A sensor network
application may need to alter its behavior to manage
limited resources more efficiently, recover from broken network links,
or change its functional behavior in response to
commands issued by an operator.

Since sensor nodes (complete with sensing data collection, processing,
and transmission) are untethered and typically must run
on small batteries, a primary factor in determining the utility of a
distributed sensor network is how well it manages energy.
Hence, the adaptations considered here focus on allowing a sensor
network to adapt energy consumption in ways that increase
longevity in exchange for reduced fidelity, increased latency or
weakened security.

Currently, most sensor nodes are software based, which provides the
flexibility necessary for adaptation. A variety of programs
can be stored in a node's local memory, or a base station can wirelessly
distribute programs for necessary adaptations.
However, a processor executing software is far less efficient (in terms
of energy consumption, manufacturing cost per unit, and
performance) than a fixed-logic ASIC. On the other hand, an ASIC does
not have the flexibility for node-level adaptation.

This paper explores the use of field-programmable hardware in sensor
nodes, which provides node flexibility with significantly
greater energy efficiency than software. Just as with the software-based
approach, node behavior and non-functional properties
can be altered using locally stored or broadcasted configuration
data. Experimental results reveal that node adaptability is
maintained with significant energy efficiency improvements (and
therefore increased network lifetime) over processor-based
nodes.